1. Field Of The Invention
One embodiment of the present invention relates to an oscillator circuit such as a voltage-controlled oscillator. Furthermore, one embodiment of the present invention relates to a semiconductor device such as a voltage-controlled oscillator.
Note that one embodiment of the present invention is not limited to the above technical field. The technical field of one embodiment of the invention disclosed in this specification and the like relates to an object, a method, or a manufacturing method. Furthermore, one embodiment of the present invention relates to a process, a machine, manufacture, or a composition of matter. Specifically, examples of the technical field of one embodiment of the present invention disclosed in this specification include a semiconductor device, a display device, a liquid crystal display device, a light-emitting device, a lighting device, a power storage device, a memory device, a method for driving any of them, and a method for manufacturing any of them.
2Description of the Related Art
A voltage-controlled oscillator (VCO) has a function of controlling oscillation frequency of an output signal according to a potential of an input signal, and is used for a phase-locked loop (PLL), a DC-DC converter, or the like. A ring oscillator based voltage-controlled oscillator, which makes an output signal oscillate by utilizing a signal delay time in a circuit, has an advantage of being able to have a layout area smaller than a voltage-controlled oscillator using an LC resonance circuit.
The following Patent Document 1 discloses a voltage-controlled oscillator in which output oscillation frequency is changed by a voltage applied to an input terminal. The following Patent Document 2 discloses a voltage-controlled oscillator that includes a plurality of transfer gates for adjusting delay time in a ring oscillator circuit forming a VCO and adjusts the delay time in the ring oscillator circuit by switching between the transfer gates.